There are new tensions between the U.S. and Turkey, a key NATO ally, after national security adviser John Bolton came here to discuss the timing of the U.S. withdrawal from Syria. Bolton was looked for assurance that when the U.S. pulls its roughly 2,000 troops out of neighboring Syria, the Turkish will not attack Syrian allies of the U.S. on the ground, CBS News reported.

Instead, an angry Turkish President Recep Tayyip Erdogan accused Bolton of making a "serious mistake" after mixed messages on the U.S. withdrawal plan.

U.S. partners in Syria are fighters from a local militia group still battling ISIS holdouts in the desert. But Turkey views them as a terrorist organization, and says it has drawn up plans to attack them.

Less than a month after President Trump announced that American troops in Syria would be coming home, there's now confusion over exactly when they'll withdraw, leaving U.S. allies unsettled in the Middle East.